[R] TRUE/FALSE as numeric values

[Prof Brian Ripley]

It is inefficient to use which() rather than a logical index, since you 
allocate two numeric index vectors (one the length of the original 
vector) and use an interpreted function rather than optimized C code.
Also, in this usage which() handles NAs incorrectly.

I think the clearest answer is probably

    with(RSF_EU, AREA[AREA <= x])

On Fri, 23 Feb 2007, Henrique Dallazuanna wrote:

> You can also:
>
> test <- RSF_EU[which(RSF_EU$AREA<=x),]
>
> On 23/02/07, Thomas Preuth <preuth at slf.ch> wrote:
>>
>> Hello,
>>
>> I want to select in a column of a dataframe all numbers smaller than a
>> value x
>> but when I type in test<-(RSF_EU$AREA<=x) I receiv as answer:
>>> test
>> [1]  TRUE FALSE FALSE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE
>> FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
>> [18]  TRUE  TRUE  TRUE  TRUE FALSE FALSE  TRUE  TRUE  TRUE  TRUE  TRUE
>> TRUE  TRUE FALSE  TRUE  TRUE  TRUE
>> [35] FALSE  TRUE  TRUE  TRUE  TRUE FALSE FALSE FALSE  TRUE  TRUE FALSE
>> TRUE  TRUE FALSE FALSE  TRUE FALSE
>> [52]  TRUE  TRUE  TRUE  TRUE  TRUE FALSE  TRUE  TRUE FALSE  TRUE
>>
>> How can i get the values smaller than x and not the TRUE/FALSE reply?
>>
>> Thanks in advance,
>> Thomas
>>
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>
>
>
>

-- 
Brian D. Ripley,                  ripley at stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
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